Increased Neonatal Complications

Many infants born after 34 weeks’ gestation do not require intensive care and room-in with their mothers or are cared for in intermediate care units. Those that are admitted to the NICU for respiratory distress, temperature instability, hypoglycemia, infection, hyperbilirubinemia, or feeding problems tend to improve within days. Overlooking the vulnerability of larger preterm infants by failing to recognize their prematurity or failing to monitor and address their specific needs can be catastrophic. Claudine Amiel-Tison views these infants, whom she calls “macropremies,” as “underprivileged newborns.”¹ Whether we call them macropremies, near-term infants, or late-preterm infants, there is no doubt that their relative immaturity makes them vulnerable to complications; they have higher mortality, morbidity, and neurodevelopmental disability rates than do full-term neonates.²

Obstetric and neonatal intensive care advances have progressively lowered the limit of viability, but most (71%) preterm infants are born at gestational age (GA) 34 to 36 weeks and 13% are born at GA 32 to 33 weeks. In contrast, infants born before 28 weeks’ gestation constitute only 2% of live births and 6% of preterm births.³

At each week of GA, there is individual variation in size and degree of maturity: just as a 10-year-old can be tall or short for age, a newborn can be large for gestational age (LGA) or small for gestational age (SGA) and more or less mature than other infants born at the same GA. A 35-week gestational age infant may be able to suck well, maintain his/her temperature with bundling, and go home with his/her mother. Another infant born at GA 35 weeks may develop hypoglycemia, temperature instability, feeding problems, respiratory distress, hyperbilirubinemia, apnea, patent ductus arteriosus, or sepsis. As a group, infants born at GA 33 to 36 weeks have three to four times the neonatal complication rate as full-term neonates. Hyperbilirubinemia is twice as common and often more prolonged in near-term infants than in full-term infants. Coordination of sucking, swallowing, and breathing improves with GA. Lower muscle tone and lower exercise tolerance in late-preterm infants contributes to poor feeding, which in turn may lead to dehydration and higher bilirubin levels.

As a result of these complications, population studies demonstrate higher mortality rates, longer mean hospital stays, and higher hospital costs in late-preterm infants than in full-term neonates. Most infants born before 35 weeks’ gestation are admitted to a NICU, and NICU admission rates decrease from approximately 50% at GA 35 weeks to 2% to 3% after 37 weeks’ gestation. Neonatal mortality rates (death before 28 days) and infant mortality rates (death before 1 year) are three to four times higher in late-preterm infants than in full-term infants. Infants born at GA 34 to 36 weeks have higher rates of rehospitalization soon after discharge than full-term neonates.⁴